1. Field of the Invention
The present invention relates to a catadioptric light distribution system for collimating a hemispherical pattern of light distributed by a lambertian light emitting diode into a collimated beam of light directed essentially along the optical axis of the LED. More particularly, the present system relates to a catadioptric light distribution system that can be used to culminate a beam light from an LED for automotive lighting purposes.
2. Detailed Description of the Prior Art
Light emitting diodes, commonly called LEDs, are well known in the art. LEDs are light producing devices that illuminate solely as a result of electrons moving in a semi-conductor material. Consequently, LEDs are advantageous as compared to filament type bulbs because an LED has no filament to burn out. Consequently, LEDs generally have a life as long as a standard transistor, and as a result have been utilized in a variety of different devices where longevity of the light source is important. Originally, LEDs were quite small and limited in their capacity to produce light. However, advances in the technology have increased the amount of light (luminous flux (Lm) or radiometric power (mW)) that an LED is capable of producing. Consequently, practical applications for LEDs have been expanded to include automotive lighting purposes.
Lambertian LEDs are also well known in the art. LEDs typically have a hemispherical top that is centered on an optical axis through the center of the LED, however other top surfaces can be used. The light emitted by the Lambertian LED is in a hemispherical pattern from 0° to approximately 90° measured from the optical axis and 360° around the optical axis. In addition, LEDs are typically mounted on a heat sink that absorbs the heat generated by the LED when it is producing light.
Unfortunately, conventional optical systems cannot culminate all of the light emitted by a Lambertian LED because of the wide spread of light emitted by and physical constraints of a Lambertian LED. For example, U.S. Pat. No. 6,558,032-Kondo et al. illustrates one prior art attempt to effectively distribute light from a Lambertian LED. However, the various light distribution systems illustrated in Kondo et al. are not very effective in collimating the light from an LED into an effective beam.
Accordingly, it is a primary object to the present invention to provide a catadioptric light distribution system that effectively collimates substantially all the light emitted by a Lambertian LED into a beam of light essentially parallel to the optical axis of the LED.